1. Field of the Invention
The present invention relates to a method for generating dynamically feasible motion of a link system having a human-like construction. This method can be used for motion generating software for a humanoid robot, a real time control system for a humanoid robot and a motion generating software for computer graphics.
2. Description of Related Art
Human models in computer graphics (CG) and humanoid robots have a significant unbalanced motion caused by bipedal locomotion, so that feasible motion is limited by contact force from an environment such as a floor, and a torque generated at a joint. Therefore, in such a humanoid, if a feasible motion can be generated previously, control for an actual humanoid robot there will readily be achieved. Moreover, in the field of CG animation, there will easily effect the artificial animation by generating a physically nonartificial motion automatically.
For example, at a motion generating of humanoid robot, there will have a large merit if the motion will be ensured to be realized dynamically for an ideal model, the control of the motion is facilitated. However, since many humanoid robot has a number of joints, there are problems such as a complexity of operation caused from variables to deal with, difficulty of real time processing caused by means of too many calculated amount.
There have been proposed many prior arts, for example, a method to adjust parameters to realize the motion dynamically by representing the motion as function (Q. Huang, K. Kaneko, K. Yokoi, S. Kajita, and T. Kotoku: “Balance Control of a Biped Robot Combining Off-line Pattern with Real-time Modification”, Proceedings of International Conference on Robotics and Automation, pp.3346–3352, 2000. and K. Nishiwaki, T. Sugihara, S. Kagami, M. Inaba, and H. Inoue: “Online Mixture and Connection of Basic Motions for Humanoid Walking Control by Footprint Specification”, Proceedings of IEEE International Conference on Roboitics and Automation, pp. 4110–4115, 2001.), a method for generating dynamically feasible motion based on motion capture data (K. Yamane and Y. Nakamura: “Dynamics Filter—Concept and Implementation of On-Line Motion Generator for Human Figures”, Proceedings of IEEE International Conference on Robotics and Automation, pp.688–695, 2000. and A. DasGupta and Y. Nakamura: “Making Feasible Walking Motion of Humanoid Robots from Human Motion Captured Data”, Proceedings of International Conference on Robotics and Automation, pp.1044–1049, 1999.).
However, these methods have the following problems:    (1) Generating only particular kinds of motion    (2) Motion becomes artificial    (3) Calculation time is too long    (4) Difficult to adjust parameters    (5) Needs reference motion data    (6) Non-interactive
Japanese patent application number 2001-242435 “Method for Generating Pose and Motion of link System with Tree Construction” invented by the same inventors as of this invention and filed by the same applicant as this application as a relative invention of this invention discloses a method, which is able to generate motion without reference data. However, this method does not regard dynamics of motion of the link system, so there is possibility to generate a physically improbable motion.
It is therefore an objective of the present invention to provide a method for generating motion of a link system, this method achieves to generate a motion interactively where the motion is realized by a human type link system such as a human model with a large number of degrees of freedom or a humanoid robot. Specifically, the objective of this invention is to provide a method which achieves that one or more of a human type link system designated by an operator moves on a trajectory given by any interface satisfying a dynamic constraint condition as follows:    (A) Fixing absolute position of link    (B) Joint value does not deviate from its predetermined movable region    (C) Joint value comes close to predetermined object value as much as possible, and that generates a whole body motion of the link system, which the system is feasible dynamically. At this point, the term “feasible dynamically” means that the motion can be executed by the driving force of a joint and contact force acted from an environment around the link system, such as a floor.